Method for quench hardening elongated workpieces

ABSTRACT

A method and apparatus for quench hardening a plurality of successive elongated workpieces supported on a carrier and movable in a generally circular path from a loading station, to a heating station, and then through a quench hardening station wherein the members supporting the workpieces on the carrier are independently movable with respect to the other members of the carrier, at least in the vicinity of the quenching station.

United States Patent [191 Sheetz METHOD FOR QUENCH HARDENING ELONGATED WORKPIECES [75] Inventor: Richard S. Sheetz, Shaker Heights,

Ohio

[73] Assignee: .Park-Ohio Industries, Inc.,

Cleveland, Ohio [22] Filed: Sept. 8, 1972 211 App]. No.: 287,543

' I Related U.S. Application Data [62] Division of Ser. No. 77,278, Oct. 1, 1970.

[52] U.S. Cl. 148/153, 148/150 [51] Int. Cl C2ld 1/18 [58] Field of Search 148/153, 143, 150,

[56] l References Cited UNITED STATES PATENTS 3,293,086 12/1966 Seulen et a1. 148/153 Nov. 27, 1973 Primary Examiner-Richard 0. Dean Attorney-Robert V. Vickers 5 7 ABSTRACT 1 Claim, 3 Drawing Figures METHOD FOR QUENCH HARDENHNG ELONGATED WORKPIECES This is a division, of U.S. Pat. application Ser. No. 77,278 filed Oct. 1, 1970 now US. Pat. No. 3,705,715.

This invention relates to the art of induction heating and quench hardening a workpiece, and more particularly to a method and apparatus of quench hardening a succession of workpieces in a continuous fashion.

The' invention is particularly applicable for quench hardening'the body of an axle shaft, and it will be described with particular reference thereto; however, it should be appreciated that the invention has much broader applications and may be used for quench hardening various other elongated workpieces, such as the bearing surfaces of a crankshaft.

For several years, it has been suggested to harden the body of an axle shaft by rotating the axle shaft adjacent an induction heating inductor. Thereafter, the heated axle shaft was quench'hardened by spraying a quenching fluid onto the heated body or'by moving the axle shaft into a quench tank. The present invention relates to a system of the type using a quench tank into which the axle shaft is moved after the body has been inductively heated. At first, this type of system, using a quench tank, involved a heating station above the tank. The axle shaft was rotated adjacent appropriate inductors to heat thebearing surfaces. Thereafter, the axle shaft was moved downwardly into the quench tank. This operation was somewhat time consuming, andefforts were made to increase the producitivity of such a system for heating and quench hardening an axle shaft by using a quench tank. It was suggested to use a carrier having a plurality of workpiece holding members extending outwardly from a common axis. An axle shaft was placed onto each of these members, and the shafts were successively heated and quenched by indexing the heated axle shafts into a quench tank. After the shafts were quench hardened, the carrier was unloaded and a new group of shafts were loaded onto the carrier. This operation again consumed a substantial amount of time. To overcome this, the use of two oscillating workpiece carriers was suggested. One-carrier was loaded with a shaft and the shaft was heated .while theother carrier was within the quench tank hardening a previously heated shaft. Thereafter, the heated axle shaft was moved into the quench tank while the hardened axle shaft was withdrawn from the tank and unloaded from the carrier. Thereafter, this cycle was repeated. Again, this did not provide a completely continuous operation.

It was then suggested to provide a carrier having at least three workpiece receiving members and movable about a common axis so that the members were successi vely indexed between a loading station, a heating station and a quenching station within a quench tank. At the loading station, the hardened workpiece was removed and an unhardened workpiece was inserted. At this same time, a workpiece at the heating station was being inductively heated. After an unheated workpiece was placed onto the member at the loading station, the carrier was indexed. This plunged the inductively heated workpiece into the quench tank and moved the unhardened workpiece to the heating station. By repeating this process, successive workpieces were hardened. This type of apparatus did provide substantially continuous operation; however, it exhibited one distinct disadvantage. Unloading and loading an axle shaft onto the carrier at the loading station often required more time than the heating cycle. This was especially true when the loading and unloading was manually performed. Consequently, this type of apparatus required an auxiliary spray quench so that the quenching operation could commence immediately after the heating cycle, irrespective of whether an operator had removed the workpiece and replaced it with an unheated workpiece at' the loading station. It was impractical to plunge'the heated workpiece into the quench tank immediately after the heating cycle terminated due to the delay at the loading station. If the quench spray arrangement was not included, the hardness of thepreviously heated bearing surfaces would not be satisfactory. The temperature would be reduced or the heating pattern would be conducted inwardly to a depth unsatisfactory for a hardened bearing surface. As another approach the heating cycle was started later or after the loading was completed. This required more controls and increased the indexing time.

All of these disadvantages of prior arrangements for quench hardening an elongated workpiece, such as an axle shaft, have been overcome by the present invention which utilizes the continuous carrier concept, but provides for immediate quenching after the heating cycle irrespective of other unfinished tasks. In accordance with the present invention, there is provided a carrier for moving an elongated workpiece in a generally circular path from a loading station, to an induction heating station and then through a quenching station. This carrier hasat least three members for supporting the workpieces and means for allowing independent movement of each of the members with respect to the other members of the carrier, at least from the heating station to the quenching station. By constructing a carrier in this manner, the workpiece may be immediately quenched without affecting the indexing operation of the carrier itself.

In accordance with another aspect of the present invention, there is provided a method of inductively heating and quench hardening an elongated workpiece which method includes the steps of providing a carrier having at least' three workpiece receiving members; moving the members, in a path defining a circle about an axis, from a loading station, to a heating station and then through a quenching station; loading a workpiece into one of the members at the loading station; indexing the carrier to move the workpiece into the heating station; inductively heating the workpiece at the heating station; and, moving the workpiece through the can be moved independently of the carrier from the heating station to the quenching station without being removed from the carrier.

Another object of the present invention is the provision of a method and apparatus for quench hardening an elongated workpiece which method and apparatus includes the use of a carrier for moving a workpiece from a loading station, to a heating station and through a quenching station, wherein the workpiece can be moved independently of the carrier in the quenching station to provide uniform quenching.

These and other objects and advantages will become apparent from the following description taken with the accompanying drawings in which:

FIG. 1 is a schematic view illustrating the present invention;

FIG. 2 is a schematic, enlarged cross-sectional view showing one feature of the preferred embodiment of the present invention; and,

FIG. 3 is an enlarged partial, schematic view taken generally along line 33 of FIG. 2.

Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only and not for the purpose of limiting same, the figures show an apparatus A for inductively heating and then quench hardening a workpiece B, in the form of an axle shaft, in a quench tank C filled by a quenching fluid to a level 10. As shown in FIG. 1, apparatus A includes a loading station I, a heating station II, and a quenching station III. A schematically illustrated carrier includes three radially extending support arms 22, 24, 26. The carrier is indexed by a means, not shown, about an axis a. In accordance with the present invention, which will be described later in more detail, each of the arms 22, 24, 26 can be indexed into the positions shown in solid lines or independently moved with respect to the carrier.

In operation, the workpiece B is loaded onto one of the arms at station. The carrier is then indexed to bring this workpiece to position II. At that position, well known induction heating inductor D is used for inductively heating the body of axle shaft B. Immediately after the heating cycle has been completed, the arms carrying the heated workpiece are moved downwardly into the quench tank C, independently of movement of the carrier itself. This is shown in phantom position at the left. Consequently, the quenching can take place immediately after the heating without waiting for loading of a subsequent workpiece onto the carrier at position I. After the workpiece is moved into the quench tank, it is then moved further to the solid line position of arm 26. This requires the upward swinging movement of the workpiece which had been assuming this position. As soon as the workpiece has been loaded at position I, the carrier 20 is indexed which raises one of the arms into position I, moves the other arm into position II, and retains the previously heated workpiece in the solid line position within tank C. This operation is continued. Two advantages are realized. First, without indexing the carrier 20 the heated workpiece can be immediately moved into the tank C. In addition, the speed of movement of the heated workpiece to the solid line position within the tank can be more gradual than that determined by the indexing speed of the carrier 20. It is appreciated that more than three support arms could be provided for the carrier 20 without departing from the intended spirit and scope of the invention. In addition, it should be realized that each support arm 22, 24, 26 is arranged in pairs with the second support arm on the opposite end of the workpiece, and not shown in the FIGURES.

A variety of structures could be used for providing independent movement of the support arms with respect to the carrier to accomplish the purposes described above. In accordance with the illustrated embodiment of the invention, as shown in FIGS. 2 and 3, the apparatus A includes an internal support shaft 30 which is stationary. Rotatable sleeves 32, 34, 36 are joumalled to rotate as a unit, or independently about the support shaft 30. Each of the sleeves has relatively small mounting elements 40, 42, 44 for arms 22, 24, 26, respectively. The remainder of the circumference of the sleeves adjacent the mounting elements is removed to allow relative movement of the respective support arms. As shown in FIG. 3, the workpiece B is supported between two axially spaced support arms, only one of which is shown, as support arm 22. When an axle shaft is being quench hardened, the workpiece B includes body 50, and is supported to be rotated about axis b by support head 52. This head includes appropriate means for rotating the workpiece at the heating station while inductor D is positioned adjacent the body 50. A wide variety of control structures could be used for effecting the movement discussed with respect to FIG. 1. In the illustrated embodiment, the sequencer 60 is used to rotate pinion gears 70, 72, 74 secured onto the terminal ends of sleeves 32, 34, 36, respectively. It is also appreciated that one drive unit could be provided for indexing the carrier 20 while separately controlled devices could be used for effecting independent movement of the respective workpiece receiving arms. In accordance with the illustrated embodiment, which is schematic in nature, the sequencer 60 effects both the indexing movement and the controlled independent movement of the respective sleeves, and thus the respective arms. Various other arrangements could be devised for accomplishing this same purpose. Since this feature does not form an element of the present invention, the schematic illustration is used for simplicity.

Having thus defined my invention, I claim:

1. A method of inductively heating and quench hardening an elongated workpiece, said method including the steps of:

a. providing a carrier having at least three workpiece receiving members;

b. moving said members, in a path defining a circle about an axis, from a loading station, to a heating station and through a quenching station;

c. loading a workpiece onto one of said members at said loading station;

d. indexing said carrier to move said workpiece into said heating station;

e. inductively heating said workpiece at said heating station; and,

f. moving said workpiece to said quenching station independently of said other members on said carrier. 

